97th DOG Annual Meeting 1999
V 697
MACULAR SPARING IN HEMIANOPIA:
ITS DEFINITE SIGNATURE AND ITS FUNCTIONAL SIGNIFICANCE
S. Trauzettel-Klosinski 1, J. Reinhard 2
It has been controversial, if macular sparing in hemianopia really exists or
if it is mimicked by unstable fixation during conventional perimetry, where
fixation control is insufficient. The aim of the study was to measure the
vertical field border in hemianopia during simultaneous and continuous
fixation control and to relate the results to other clinical parameters.
Methods: A Scanning Laser Ophthalmoscope (SLO) was used to image the fundus
and to present stimuli. Vertical triplets of dots were scanned onto the
retinae of 10 patients (17 eyes) at different eccentricities from the
vertical midline during simultaneous monitoring of the foveola position.
Fixation stability and locus were measured by continuous registration of the
fixational eye movements and the retinal fixation locus during fixation of a
cross. Conventional perimetry was performed by Tuebingen Manual and
Automated Perimeter. In addition, eye movements during reading texts were
recorded by SLO and an infrared reflection system.
Results: In 5 patients absence of sparing, in 5 patients macular sparing of
2-8° was found. The latter had occipital lesions with sparing of the
occipital pole. The larger the sparing, the better were fixation stability,
agreement with conventional perimetry and reading speed. Patients without
sparing showed eccentric or central unstable fixation with frequent saccades
towards the hemianopic side - both causing a shift of the entire field
border in conventional perimetry.
Conclusions: Macular sparing exists and can be determined exactly. Its
occurrence depends on the site of the lesion. Its size is of significance
for fixation behavior, the reliability of conventional perimetric results
and reading performance. Eccentric fixation, an adaptive strategy, creates a
perceptual area on the hemianopic side, which is especially useful for
reading. The presented method offers a reliable instrument to evaluate
residual central vision as well as potential effects of training programs
under exact fixation control.
Supported by German Research Council (DFG Zr/13-1) and fortüne 294
1 Dept. of Pathophysiology of Vision and Neuro-Ophthalmology,
2 University Eye Hospital, Schleichstr. 12-16, D-72076 Tübingen
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